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Allylic carbonates are cyanated in high yields to β,γ-unsaturated carbonitriles using trimethylsilyl cyanide in the presence of a catalytic amount (5 mol %) of Pd(PPh3)4 in THF under reflux. In the reaction, cinnnamyl methyl carbonate affords cinnamyl cyanide in 98% yield. Allylic acetates also provide the corresponding carbonitriles, but often in lower yields. The cyanations of several cis- and trans-alicyclic substrates proceed cleanly (stereoselectivity > 99%) with overall retention. Characterization and reaction of palladium complexes relevant to the present catalysis indicate that transmetalation of an η3-allyl palladium complex with trimethylsilyl cyanide is facile, while the resulting cyano(η3-allyl)palladium complexes afford the corresponding allylic cyanides only when excess trimethylsilyl cyanide is present. Stereochemistry of the product indicates that the CN attacks the η3-allyl moieties from the palladium side.

Allylic carbonates are cyanated in high yields to β,γ-unsaturated carbonitriles using trimethylsilyl cyanide in the presence of a catalytic amount (5 mol %) of Pd(PPh3)4 in THF under reflux. In the reaction, cinnnamyl methyl carbonate affords cinnamyl cyanide in 98% yield. Allylic acetates also provide the corresponding carbonitriles, but often in lower yields. The cyanations of several cis- and trans-alicyclic substrates proceed cleanly (stereoselectivity > 99%) with overall retention. Characterization and reaction of palladium complexes relevant to the present catalysis indicate that transmetalation of an η3-allyl palladium complex with trimethylsilyl cyanide is facile, while the resulting cyano(η3-allyl)palladium complexes afford the corresponding allylic cyanides only when excess trimethylsilyl cyanide is present. Stereochemistry of the product indicates that the CN attacks the η3-allyl moieties from the palladium side.

This paper summarizes recent works in which the entanglement effect on diffusion and viscoelasticity was mainly studied on solutions of narrow‐distribution polystyrene (PS) in dibutylphthalate (DBP) over a wide range of temperature T, concentration C, and molecular weight M. The temperature dependence of the self‐diffusion coefficient Ds and the tracer diffusion coefficient Dtr was described by the WLF equation with values of the WLF coefficients the same as found for the solution viscosity η. The effects of entanglements on the self‐diffusion behavior and the viscoelastic behavior were examined from data analysis in terms of the two parameters, the effective friction coefficient of a segment ζ and the molecular weight between entanglements Me. The product Dsη/C was close to the theoretical prediction based on the free Rouse chain up to M/Me∼1 and, for M/Me≳10, showed universal behavior characterized by the linear proportionality to M/Me. The ratio of the two characteristic times for viscoelasticity and d...

The self diffusion coefficient Ds of two labeled polystyrene (PS) samples in dibutyl phthalate (DBP) has been measured in the range of polymer concentration from 0.1 to 50 wt% using forced Rayleigh scattering (FRS) and fluorescence recovery after photobleaching (FRAP). 2-Nitro-4-carboxy-4′-dimethylaminostilbene and 4-glycyl-7-nitrobenzofurazan have been used as photochromic dyes for FRS and FRAP measurements, respectively. Good agreement has been found between two sets of Ds data in the range of Ds from 10−8 to 10−12 cm2 s−1 within experimental error. In the dilute region of c≤1 wt%, mutual diffusion coefficient D of unlabeled but otherwise the same PSs in DBP has been measured by dynamic light scattering. The Ds assymptotically approached D with decreasing polymer concentration.

Etude par diffusion de Rayleigh forcee de solutions a 40% de PS de masse moleculaire du coefficient d'autodiffusion des PS, de diffusion du traceur et de la viscosite avec celle des coefficients du PS tendu et avec les previsions theoriques

Self Diffusion of Polymers in the Concentrated Regime I. Temperature Dependence of the Self Diffusion Coefficient and the Steady Viscosity of Polystyrene in Dibutyl Phthalate